PHOENIX — The coronavirus pandemic is a cause for concern for families who face various policies at schools and day care centers.

The spread of the more infectious delta variant, particularly among people who refuse vaccinations, has caused an increase in infections in children. The coronavirus exposures and illnesses at schools and day cares can mean children get sent home, forcing parents to scramble for childcare.

There’s evidence that masks in schools help reduce virus spread, and most Americans support requiring masks for students and teachers. District policies on masks, testing and quarantines vary widely. Soon after schools reopened in August, the rate of coronavirus infections forced dozens of districts to back off in-person learning.

More than 5.5 million children in the U.S. have tested positive for the coronavirus, with 20% of all child cases coming since this school year began, according to the American Academy of Pediatrics. Kids are at lower risk of severe illness or death, but at least 498 have died.

Vaccines have been available for children as young as 12 since May, but vaccination rates trail adults. Federal data show about half of 16- and 17-year-olds are vaccinated, while 43% of 12- to 15-year-olds are vaccinated; two-thirds of adults are vaccinated.